Liquid fuel pumps



F. G. FREEMAN LIQUID FUEL PUMPS I July 16, 1963 Filed Feb. 28, 1961 2Sheets-Sheet 1 July 16, 1963 Y F. s. FREEMAN LIQUID FUEL PUMPS 2Sheets-Sheet 2 Filed Feb. 28, 1961 United States Patent 3,097,607 LIQUIDFUEL PUMPS Frank G. Freeman, Solihull, England, assignor to Joseph Lucas(Industries) Limited, Birmingham, England Filed Feb. 28, 1961, Ser. No.92,220 Claims priority, application Great Britain Mar. 1, 1960 1 Claim.(Cl. 10341) This invention relates to pumps for supplying liquid fuel togas turbine or other engines, the pump being of the kind comprising incombination a hollow body pant having an inlet and outlet, a rotormounted in the body part for rotation by the engine, a plurality ofplungers occupying a plurality of bores in the rotor respectively, and acam surface against which the plungers are urged, the arrangement beingsuch that as the rotor is rotated, fuel will flow from the inlet intothe bores in turn during the "outward movements of the plungers and bedischarged through the outlet by the inward movements of the plungersdue to their interaction with the cam surface.

The object of the invention is to combine with such a pump convenientmeans for governing the speed of the engine.

According to the invention a pump of the kind specified includes a bleedpassage in communication with the pump outlet, a valve member forcontrolling the escape of fuel through said bleed passage, said valvemember being rotatable with, but axially movable relative to, the rotor,and centrifugally operable means on the rotor for moving said valvemember axially in a direction to uncover said bleed passage as the speedof the engine increases.

More specifically the valve member comprises a piston movable in acylinder by said centrifugally operable means, the bleed passageterminating in the wall of the cylinder and the pump further including arestricted orifice through which the inner end of the cylinder is incommunication with the pump outlet, and an adjustable relief valve forcontrolling the pressure of fuel in the inner end of the cylinder, andhence the engine speed at which the bleed passage is uncovered.

An example of the invention is illustrated in the accompanying drawingsin which FIGURE 1 is a sectional side view, FIGURES 2, 3 and 4respectively are sections on the lines 2-2, 3-3 and 4-4, in FIGURE 1,and FIG- URE 5 is a section on the line 5-5 in FIGURE 4.

Referring to the drawings, the pump illustrated is intended forsupplying liquid fuel to a gas turbine engine for a road vehicle, andcomprises a hollow body part 6 provided with a fuel inlet 7 and a fueloutlet 8. Within the body part is a rotor 9 which is mounted or formedon a shaft 10 extending at one end from the body part 6 and adapted tobe driven by the engine. In the rotor 9 are formed a plurality ofangularly spaced parallel bores 9a extending parallel to the shaft 10.In each bore is a plunger 11 having at one end a shoe 12 which is heldby one of a plurality of springs 13 against a cam surface 14 disposedobliquely to the axis of the shaft 10. Moreover at the end of the rotor9 remote from the cam surface 14 is formed on the body part 6 asegmental valve (FIGURE 2) in which is formed an arcuate port 15 incommunication with the outlet 8, the arrangement being such that as therotor 9 is rotated fuel will be drawn into the bores 9a in turn by theoutward movements of the plungers 11 under the action of their springs13 and will be discharged through the port to the outlet 8 as theplungers 11 are moved inwardly by the cam surface 14.

In the end of the body part 6 containing the cam surface 14 there isformed a valve cylinder 16 which is coaxial with the rotor 9. In thecylinder 16 is a piston 17 having a stem 18 which extends into thecentre of the rotor and is provided with a foot 19. The piston 17 is3,097,607 Patented July 16, 1963 ice spring-loaded towards the rotor bymeans of a coiled compression spring 20 acting between the foot 19 andan abutment ring 21 in the rotor, and on the rotor is pivoted acentrifugally operable mass 22 which, as the angular velocity of therotor increases, is adapted to exert an increasing axial force on thefoot 19 through the intermediary of a ball 23, this force acting inopposition to the spring 20.

In the wall of the cylinder 16 is an annular groove 24 which is coveredby the piston 17 when the pump is at rest, and which is in communicationwith the pump outlet 8 through a bleed passage 25 (FIGURE 5)communieating with a further passage 26. The passage 26 is also incommunication with the other end of the cylinder 16 through a restrictedorifice 27 (FIGURE 5) and a further passage 28. Moreover for controllingthe pressure of fuel in the inner end of the cylinder there is provideda relief valve (FIGURE 4) the setting of which can be adjusted by thedriver.

The relief valve takes the form of a stepped cylinder 29 formed withinthe body part and extending at right angles to the axis of the rotor.The narrower end of the cylinder is connected to the passage 28 andcontains a cylindrical valve member 30 having a head adapted to seatagainst a shoulder defined between the narrower and wider part of thecylinder. The valve member 30 is loaded against its seating by means ofa coiled compression spring 31 interposed between its head and anabutment piston 32 in the wider part of the cylinder, and between thevalve member and the abutment piston is an outlet 33 through which fuelcan escape through a passage 34 to the inlet side of the pump.

The wider end of the cylinder 29 is adapted for connection to a cylinderor other device (not shown) Whereby fluid pressure can be applied to theopposite side of the piston 32 in accordance with the setting of athrottle pedal or other control operable by' the driver, the arrangementbeing such that as the control is moved to increase the speed of theengine the compression of the spring 31 increases.

The relief valve 29, 30 is operable by a predetermined pressure of thefuel in the fuel outlet 8 of the hollow body part 6, and thereby servesto reduce the pressure of the fuel which occupies the inner end of thegoverning valve cylinder 16 remote from the interior of the hollow bodypart 6, and which is supplied from the fuel outlet 8 to this end of thegoverning valve cylinder through the restricted orifice 27 for opposingopening movement of the governing valve 16, 17.

Moreover, the governing valve 16, 17 is operable under the action of thecentrifugally operable mass 22 carried by the rotor 9, and therebyserves to reduce the fuel pressure in the fuel outlet 8.

In operation the centrifugally operable mass 22 acts in opposition tothe spring 20 and also the pressure of fuel at the inner end of thevalve cylinder 16. Therefore, assuming that the drivers control is keptat a constant setting, the relief valve will open at a predeterminedspeed and permit fuel to escape fro-m the inner end of the valvecylinder 16 until the piston 17 uncovers the annular groove 24 andpermits fuel to flow from the pump outlet 8 through the passages 26, 25to the inlet 7. As a result the quantity of fuel fed to the engine isreduced and the engine speed falls thereby allowing the relief valve toclose and the pressure of fuel fed through the restricted orifice 27 tothe inner end of the valve cylinder 16 to return the piston 17 to itsinitial setting. By this means the speed of the engine will be governedto accord with the setting of the driver operated control, whichdetermines the pressure at which the relief valve opens.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

A liquid fuel pump of the kind specified, comprising in combination ahollow body provided with a fuel inlet, a fuel outlet, an internal camsurface, and a bleed passage communicating at one end thereof with saidoutlet, a rotor mounted within said hollow body, and provided with aplurality of longitudinal bores which are angularly spaced relative tothe axis of said rotor, and each of which communicates alternately, atone endof said rotor, with said inlet and said outlet during rotation ofsaid rotor, a plurality of spring-loaded plungers respectively mountedwithin said bores, and extending from the other end of said rotor intocontact with said cam surface which is disposed so that rotation of saidrotor is accompanied by reciprocation of said plungers for enabling fuelfrom said inlet to be admitted to said bores in turn, and to bedischarged from said bores in turn through said outlet, a valve memberin the form of a piston which is coaxial with said rotor, and whichserves to control the escape of fuel from the end of said bleed passageremote from said outlet, means whereby said piston is connected to saidrotor so as to be rotatable therewith, and capable of axial movementrelative thereto, centrifugally operable means which is carried by saidrotor, and under the action of which said piston is movable axially topermit escape of fuel from said bleed passage when said rotor attains apredetermined speed, a valve cylinder in which said piston is mounted,and which at one end communicates through the interior of said hollowbody with said inlet, and an adjustable pressure-responsive relief valvefor controlling pressure in the other end of said cylinder, the latterbeing provided adjacent the first mentioned end thereof with an openingwhich communicates with the end of said bleed passage remote from saidoutlet, and through the medium of which communication is establisha'blebetween said bleed passage and the first mentioned end of said cylinderby movement of said piston under the action of said centrifugallyoperable means, said hollow body being provided with a restrictedorifice in communication with said outlet, and being also provided witha second passage which communicates at opposite ends respectively withthe said other end of said cylinder and the end of said restrictedorifice remote from said outlet, and said second passage being also incommunication with said relief valve.

References Cited in the file of this patent UNITED STATES PATENTS654,140 Diesel July 24, 1900 2,251,552 Purdy Aug. 5, 1941 2,357,563Truxell Sept. 5, 1944 2,501,054 Huber Mar. 21, 1950 2,590,853 FultonApr. 1, 1952 2,706,384 Schott Apr. 19, 1955 2,922,370 Bischotf Jan. 26,1960

